Word search searches for a sequence of words without regard to how the
words are separated. More precisely, you type a string of many words,
using single spaces to separate them, and the string can be found even if
there are multiple spaces, newlines or other punctuation between the words.

Word search is useful for editing a printed document made with a text
formatter. If you edit while looking at the printed, formatted version,
you can't tell where the line breaks are in the source file. With word
search, you can search without having to know them.

C-s RET C-w wordsRET

Search for words, ignoring details of punctuation.

C-r RET C-w wordsRET

Search backward for words, ignoring details of punctuation.

Word search is a special case of nonincremental search and is invoked
with C-s RET C-w. This is followed by the search string,
which must always be terminated with RET. Being nonincremental,
this search does not start until the argument is terminated. It works
by constructing a regular expression and searching for that; see
section Regular Expression Search.

Use C-r RET C-w to do backward word search.

Forward and backward word searches are implemented by the commands
word-search-forward and word-search-backward. These
commands may be bound to keys in the usual manner. The feature that you
can get to them via the incremental search commands exists for historical
reasons, and to avoid the need to find suitable key sequences for them.